Grape: Undefined method 'to_prepare' for ActionDispatch::Callbacks:Class (NoMethodError)

[PAMulligan]

Using Rails 5.1.2, Ruby 2.4.0p0

I have an existing app, attempting to add a Grape API on top of it to call it from another app. Following the documentation, I put the following code in app/api/wlp/api.rb:

module WLP
    class API < Grape::API
        version 'v1', using: :header, vendor: 'Washington Listing Pros'
        format :json
        prefix :api

        resource :listings do
            desc 'Return all listings'
            get :listings do
                Listing.all
            end

            desc 'Return a listing'
            params do
                requires :id, type: Integer, desc: 'Listing ID'
            end
            route_param :id do
                get do
                    Listing.find(params[:id])
                end
            end
        end
    end
end

Put the following in my application.rb:

config.paths.add File.join('app', 'api'), glob: File.join('**', '*.rb')
config.autoload_paths += Dir[Rails.root.join('app', 'api', '*')]

My config/routes.rb:

Rails.application.routes.draw do
    mount WLP::API => '/'
    resources :listings, only: [:show, :new, :create, :edit]
    root 'landing#index'
    get 'contact', to: 'contact', controller: 'landing', as: :contact
end

I installed the hashie forbidden attributes gem properly. I created the config/initializers/reload_api.rb file:

if Rails.env.development?
    ActiveSupport::Dependencies.explicitly_unloadable_constants << 'Twitter::API'

    api_files = Dir[Rails.root.join('app', 'api', '**', '*.rb')]
    api_reloader = ActiveSupport::FileUpdateChecker.new(api_files) do
        Rails.application.reload_routes!
    end
    ActionDispatch::Callbacks.to_prepare do
        api_reloader.execute_if_updated
    end
end

I'm receiving the error message when I try to start the Rails server. Is this not supported for 5.1.2?

[dblock]

Call stack?

[PAMulligan]

Sorry, here ya go:

from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.1.2/lib/active_support/dependencies.rb:286:in `load'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.1.2/lib/active_support/dependencies.rb:286:in `block in load'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.1.2/lib/active_support/dependencies.rb:258:in `load_dependency'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.1.2/lib/active_support/dependencies.rb:286:in `load'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/engine.rb:655:in `block in load_config_initializer'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/activesupport-5.1.2/lib/active_support/notifications.rb:168:in `instrument'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/engine.rb:654:in `load_config_initializer'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/engine.rb:612:in `block (2 levels) in <class:Engine>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/engine.rb:611:in `each'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/engine.rb:611:in `block in <class:Engine>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/initializable.rb:30:in `instance_exec'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/initializable.rb:30:in `run'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/initializable.rb:59:in `block in run_initializers'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:228:in `block in tsort_each'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:422:in `block (2 levels) in each_strongly_connected_component_from'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:431:in `each_strongly_connected_component_from'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:421:in `block in each_strongly_connected_component_from'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/initializable.rb:48:in `each'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/initializable.rb:48:in `tsort_each_child'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:415:in `call'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:415:in `each_strongly_connected_component_from'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:349:in `block in each_strongly_connected_component'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:347:in `each'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:347:in `call'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:347:in `each_strongly_connected_component'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:226:in `tsort_each'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/tsort.rb:205:in `tsort_each'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/initializable.rb:58:in `run_initializers'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/application.rb:353:in `initialize!'
    from /home/paul/pmds/websites/listingpros/washingtonlistingpros/config/environment.rb:5:in `<top (required)>'
    from config.ru:3:in `require_relative'
    from config.ru:3:in `block in <main>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:55:in `instance_eval'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:55:in `initialize'
    from config.ru:in `new'
    from config.ru:in `<main>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:49:in `eval'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:49:in `new_from_string'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:40:in `parse_file'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/server.rb:319:in `build_app_and_options_from_config'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/server.rb:219:in `app'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands/server/server_command.rb:24:in `app'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/rack-2.0.3/lib/rack/server.rb:354:in `wrapped_app'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands/server/server_command.rb:80:in `log_to_stdout'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands/server/server_command.rb:42:in `start'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands/server/server_command.rb:131:in `block in perform'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands/server/server_command.rb:126:in `tap'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands/server/server_command.rb:126:in `perform'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/thor-0.19.4/lib/thor.rb:369:in `dispatch'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/command/base.rb:63:in `perform'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/command.rb:44:in `invoke'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/railties-5.1.2/lib/rails/commands.rb:16:in `<top (required)>'
    from /home/paul/pmds/websites/listingpros/washingtonlistingpros/bin/rails:9:in `require'
    from /home/paul/pmds/websites/listingpros/washingtonlistingpros/bin/rails:9:in `<top (required)>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in `load'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in `call'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/lib/spring/client/command.rb:7:in `call'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/lib/spring/client.rb:30:in `run'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/bin/spring:49:in `<top (required)>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `load'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `<top (required)>'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:68:in `require'
    from /home/paul/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:68:in `require'
    from /home/paul/pmds/websites/listingpros/washingtonlistingpros/bin/spring:15:in `<top (required)>'
    from bin/rails:3:in `load'
    from bin/rails:3:in `<main>'

[dblock]

Sigh, so much going on here. If you put a project up on github that reproduces this I can take a look.

[PAMulligan]

I added you as a collaborator.

[rnubel]

Rails 5.1 removed ActionDispatch::Callbacks#to_prepare (see https://github.com/rails/rails/commit/3f2b7d60a52ffb2ad2d4fcf889c06b631db1946b); so the issue lies in your reload_api.rb initializer. Replacing it with ActiveSupport::Reloader.to_prepare should fix the issue.

[dblock]

@rnubel PR a into @PAMulligan's project? Can I close this?

[PAMulligan]

I'm at work at the moment, haven't been able to confirm the fix, but if you're certain this is the answer, close away and I'll reopen if it's still an issue.

[PAMulligan]

Thank you @rnubel, that at least got the server running!

[picman]

The problem seems to be in RedmineExtensions gem.

module Reloader
    def self.to_prepare(*args, &block)
      if defined? ActiveSupport::Reloader
        ActiveSupport::Reloader.to_prepare(*args, &block)
      else
        ActionDispatch::Reloader.to_prepare(*args, &block)
      end
    end
...
end

ActiveSupport::Reloader.to_prepare(*args, &block) needs to be called.

activesupport gem installed?

[BagginsHasIt]

I've installed gem activsupport but still get an error:

NoMethodError: undefined method `to_prepare' for ActionDispatch::Reloader:Class

after running command:

bundle exec rake redmine:plugins:migrate NAME=redmine_dmsf RAILS_ENV="production"